The present invention relates to a muffling device for combustion engines, especially for two stroke engines of hand-guided working tools such as motor chainsaws, trimmers etc. Such as muffling device comprises at least one housing member with at least one outlet opening for the exhaust gas whereby a cover member covers the outlet opening for deflecting the exhaust gas stream.
From German Offenlegungsschrift 26 38 203 a muffling device for small engines is known which is comprised of a lower and an upper housing member detachably connected to one another. The exhaust gas is guided through a tube extending into the lower housing member and can exit through openings in the upper housing member. The openings are in the form of longitudinal slots and are covered by a cover member that deflects the exhaust gas.
Due to the small constructive size that such a muffling device should have, the exhaust gas flow path within the muffling device is relatively short so that the exhaust gas at the exit location into the surrounding atmosphere has a very high exhaust gas temperature. Exhaust gas streams of such high temperatures are very uncomfortable for the operator. Furthermore, very strict specifications are placed on working tools that are, for example, used in forestry, especially with respect to the exhaust gas temperature in a measuring plane in the vicinity of the exhaust gas muffling device. Furthermore, a housing part of the working tool that bridges the exhaust gas muffling device and is provided with venting slots should not be exposed to excessive temperature loads.
It is therefore an object of the present invention to improve a muffling device for combustion engines of the aforementioned kind such that with simple means and without greater expenditures a reduction of the exhaust gas temperature can be achieved.